1. Technical Field
The present invention is directed toward casement hinges for windows, and more particularly toward improved track pivots of casement hinges.
2. Background Art
The casement window has a window sash movably mounted within a frame by a pair of hinges mounted between the window frame and the top and bottom of the window sash. It is typical of such a hinge to have a track mountable to the window frame and a sash arm connectable to the window sash. A support arm interconnects the track and the sash arm, with the support arm being pivotally connected to the track and the sash arm. The sash arm is pivotally connected either directly or by means of an interconnecting link to a mounting shoe which is movably guided for movement lengthwise of the track. A window hinge of this type is shown, for example, in Tacheny et al. U.S. Pat. No. 4,726,092.
Another type of casement window hinge differs from the just-described window hinge in having the sash arm pivotally connected to the track by an intervening link, with the intervening link being pivotally fixed to the track, rather than to a movable shoe, and with a support arm pivotally connected to the sash arm also being pivotally mounted to a shoe movably guided on the track for movement lengthwise of the track. A window hinge of this type is shown, for example, in Vetter U.S. Pat. No. 4,674,149.
When window hinges of the above type are installed, proper operation and sealing of the window when closed requires that the fixed track pivot (on the window frame) be properly located relative to the window sash. Further, over the life of the window, the proper location of the fixed track pivot may change due to slight shifting of the window, window frame, etc., resulting in a sag in the sash. Sash sag is a condition formed when the sash and the frame of a window are no longer square to one another (in the closed position), or the edge of the sash which is opposite the hinges seems to sag in comparison to the frame of the window. As a result, the window may not seal tightly or open and close easily.
Heretofore, precise installation of the hinge and later correction of sash sag has required that the hinge track be provided with slotted holes and that the hinge mounting screws in the slotted holes be removed to allow for shifting of the track. Repeated removal of such screws can, however, over the life of a window result in a gradual loosening of the strength of the mounting. Further, the slotted holes, by providing only a frictional contact with the screw heads to prevent longitudinal shifting of the track, can allow the track to undesirably shift and/or loosen over the window life as a result of forces incurred from the wind, operating hardware, window weight, and even from forcing to gain improper entry through the window.
Of course, with either type of hinge as described above, it is also necessary to provide a slidable shoe which can operate smoothly and still be strong enough to withstand the substantial loads mentioned above.
The present invention is intended to avoid one or more of the problems discussed above.